It is conventional practice in the art of publication binding to arrange the papers of publications to be bound in signatures. A signature is a printed sheet of rectangular paper folded into multiples of four pages which, when folded as a unit, forms a section of a book or pamphlet. A signature is formed by folding a rectangular sheet of paper along a first axis midway between parallel edges of the rectangle, and thereafter folding the composite structure along a second perpendicular axis midway between the other two edges of the rectangular piece of paper. The folded edges of the signature are trimmed along the first fold of the signature to form four leaves of paper with a page on either side of each leaf. In some instances different paper folds may be employed to provide signatures of 2,4,8,16, 24 or 64 leaves.
In conventional practice, hardcover books are "casebound" while paperback publications are "perfect" or "adhesive" bound. In case binding the leaves of the signatures may be sewn together along the spines of the signatures. The sewing operation is performed manually or by machine, using a needle and thread. After sewing each signature, a plurality of signatures are positioned adjacent to each other in mutually parallel alignment. This is called "gathering" or "collating." In gathering, the signatures are arranged so that pagination is in seratin order. After gathering, the signatures are sewn to each other and glued together. Thus, the leaves within each signature are held by thread while the signatures are both sewn and glued together. Thereafter, an adhesive is applied to the spines of the proximately located signatures. A backing material, called a "crash" is contacted with the adhesive to hold the spines of the signatures in a relatively close array. A starched cotton fabric or adhesive tape typically serves as a "crash" and is useful in reinforcing the spine of the publication. A casebound book usually requires the outer surfaces of the pages of special end paper signatures to be glued to the inside front and back covers of the book. Conventional case binding requires considerable hand labor, particularly in sewing together the signatures. It is a relatively lengthy, arduous and expensive process, but does result in a durable bound publication.
An alternative conventional method of publication binding is perfect or adhesive binding. This method of binding is typically used in conjunction with paperback books and other softcover publications. In perfect binding, signatures are formed in the manner previously indicated. However, rather than being sewn together, the spine edges are "padded." In padding, the folded spines are trimmed from the signatures after the signatures are gathered. Adhesive is then applied along the edges of the leaves from which the spines of the signatures were trimmed. In the process of glueing the signatures are flexed in a manner which enables a tiny bead of glue to be placed on each side of the spine side of the paper, thus enhancing adhesion between the pages. The fused edges of the leaves are then pressed against the center of the paperback cover and the adhesive is allowed to dry. Adhesive applied in this manner is free to seep in between the pages of the publication a short distance before drying, and hence provides an area of bonding on the pages in addition to the area at the rear edge of each page which is glued to the cover back.
Perfect or adhesive binding is much cheaper and easier than case binding, since no sewing operations are required. However, the quality of binding effected in this manner is inferior to case binding.
It is an object of the present invention to provide an improved method of publication binding which achieves the superior quality of case binding, but without the attendant disadvantage of labor intensive steps necessary in case binding. The high quality of case binding is posssible using the invention, since the leaves of the signatures are not separated from each other, but rather opposing leaves of a signature remain joined together along the signature spine.
It is a further object of the present invention to provide a method of binding utilizing an adhesive, such as glue, rather than utilizing a relatively expensive manner of fastening pages together, such as stitching with thread. The use of glue as a means of binding pages within a publication is possible by virtue of the apertures formed along the spines of the signatures bound together. By utilizing patterns of apertures, a means is provided by which the adhesive gains access to the interior pages of the signature, yet without completely separating opposing leaves from each other. Instead, the adhesive is introduced through the apertures cut into the paper and thereby provides additional bonding surface area on the pages of the publication to hold the publication leaves immobile relative to each other adjacent to the publication backing.